Electronic electricity-taking mutual inductor

Abstract

The utility model discloses an electronic electricity-taking mutual inductor, and relates to the technical field of electric power measurement. The problems that an existing electronic transformer is poor in measurement precision and stability in a complex electromagnetic environment, power supply cannot meet the high-load requirement, and the service life of equipment is short are solved. Comprising a pre-filter circuit, a signal processing circuit, a signal isolation and amplification circuit, a composite power supply circuit, a monitoring and control circuit and a communication circuit. The pre-filter circuit enhances the anti-interference capability, the composite power supply circuit guarantees energy supply, the monitoring and control circuit realizes intelligent management, and the communication circuit supports data interaction; according to the scheme, the measurement precision and stability of the electronic power-taking mutual inductor in a severe electromagnetic environment are remarkably improved, the power supply reliability is greatly improved, and the service life of equipment is greatly prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to power measurement technical field, and more exactly relates to a kind of electronic power taking mutual inductor. BACKGROUND

[0002] With the increase of power transmission capacity and the improvement of operating voltage level, the traditional electromagnetic mutual inductor exposes problems such as high insulation requirement, magnetic saturation and ferromagnetic resonance. Electronic mutual inductor becomes the development direction of voltage and current measurement under extra-high voltage condition due to its unique advantages.

[0003] Electronic power taking mutual inductor (EVT and ECT) is based on optical and electronic principles, and has advantages in bandwidth, insulation and cost compared with traditional mutual inductor. They use optical fiber as transmission system between primary converter and secondary converter, and are equipped with electronic devices for transmission and amplification of measurement signals, with analog voltage output or digital output. The classification of electronic power taking mutual inductor includes active and passive types. Passive EVT mainly uses traditional resistance divider, capacitance divider and single capacitor to measure voltage value, while active ECT uses traditional current transformer, Hall sensor and Rogowski coil as primary current sampling sensor head

[0004] However, in actual use, the secondary side electronic circuit of electronic power taking mutual inductor is easily disturbed by other equipment in control cabinet area, especially in harsh electromagnetic environment of high-voltage substation, small voltage division signal transmission is easily disturbed, which affects measurement accuracy and stability. In addition, some electronic mutual inductors use low-voltage side optical power supply method to supply energy through large-diameter optical fiber. However, the power provided by laser is limited, and the photoelectric conversion efficiency is not high, which leads to insufficient energy supply to high-voltage side, making it difficult to meet the power demand of mutual inductor under high load operation. In addition, the service life of photocell under long-term full-load working condition is difficult to guarantee, which increases maintenance cost and equipment failure risk, and limits the long-term stable operation of mutual inductor. UTILITY MODEL CONTENT

[0005] The utility model aims to design an electronic power taking mutual inductor to solve the shortcomings in the background technology.

[0006] In order to achieve the above technical effects, the utility model adopts the following technical solutions:

[0007] An electronic power taking mutual inductor comprises a pre-filter circuit, a signal processing circuit, a signal isolation and amplification circuit, a composite power supply circuit, a monitoring and control circuit and a communication circuit.

[0008] The output end of the pre-filtering circuit is connected with the input end of the signal processing circuit; the output end of the signal processing circuit is connected with the input end of the signal isolation and amplification circuit; the output end of the composite power supply circuit is electrically connected with the input end of the pre-filtering circuit, the signal processing circuit, the signal isolation and amplification circuit and the monitoring and control circuit; the input end of the monitoring and control circuit is connected with the output end of the composite power supply circuit, the output end of the monitoring and control circuit switches the power supply mode of the composite power supply circuit through the control relay, and the communication circuit is used for data interaction with external equipment.

[0009] Further, the pre-filtering circuit comprises a common-mode inductor, a ceramic capacitor and a voltage-dependent resistor; two input lines of the common-mode inductor are connected with a small voltage division signal, the output line of the common-mode inductor is connected with one end of the ceramic capacitor, and the other end of the ceramic capacitor is grounded; the voltage-dependent resistor is connected across the small voltage division signal line and the ground.

[0010] Further, the signal processing circuit comprises a signal processing chip, an SRAM, a clock chip and a reset circuit; the analog input pin of the signal processing chip is connected with the output of the pre-filtering circuit, the signal processing chip is connected with the data pin, the address pin and the control pin of the SRAM through the data bus, the address bus and the control bus respectively; the clock input pin of the signal processing chip is connected with the clock output pin of the clock chip; the reset pin of the signal processing chip is connected with the output end of the reset circuit; the reset circuit is composed of a 10kΩ resistor and a 0.1μF capacitor.

[0011] Further, the signal isolation and amplification circuit comprises an isolation amplifier, an operational amplifier and a resistance-capacitance network; the input pin of the isolation amplifier receives the output signal of the signal processing circuit, the isolation output pin of the isolation amplifier is connected with the input pin of the operational amplifier; the operational amplifier sets the gain through the resistance-capacitance network.

[0012] Further, the resistance-capacitance network is composed of a plurality of resistors and capacitors, which is used for adjusting the gain and frequency response of the amplifier.

[0013] Further, the composite power supply circuit comprises a light power supply optimization circuit, a wireless charging circuit and a power management and energy storage circuit; the light power supply optimization circuit comprises a laser driver chip, a photoelectric converter and an MPPT circuit; the monitoring and control circuit comprises a temperature sensor, a microcontroller, a voltage and current monitoring chip and a control relay; the power management and energy storage circuit comprises a capacitor and a power management chip; a laser driving output pin of the laser driver chip is connected to a laser, laser is converted into electric energy by the photoelectric converter and input to the MPPT circuit; an output end of the MPPT circuit is connected to a VIN pin of the power management chip and connected to a control pin of the laser driver chip through a control signal line; a transmitting end and a receiving end of the wireless charging circuit transmit energy through wireless signals, and an output of the wireless charging circuit is connected to another VIN pin of the power management chip; the capacitor is connected to a CAP+ pin of the power management chip; and the output end of the power management chip supplies power to the pre-filter circuit, the signal processing circuit, the signal isolation and amplification circuit and the monitoring and control circuit.

[0014] Further, the monitoring and control circuit comprises a microcontroller, a voltage and current monitoring chip, a temperature sensor and a control relay; the microcontroller adopts an STM32F407VET6; an input end of the voltage and current monitoring chip is connected to an output end of the composite power supply circuit, and output ends of the voltage and current monitoring chip and the temperature sensor are connected to input ends of the microcontroller; an output end of the microcontroller is connected to an input end of the control relay, and the control relay is connected to a power supply line of the composite power supply circuit.

[0015] Further, the communication circuit comprises a fiber communication module, an RS485 communication chip and a level conversion chip; an output end of the fiber communication module is connected to a receiving device of a remote monitoring center; A and B pins of the RS485 communication chip are connected to an RS485 bus of other local power equipment; a control pin and a data pin of the RS485 communication chip are connected to GPIO pins and serial communication pins of the microcontroller; and input and output pins of the level conversion chip are connected to serial communication pins of the microcontroller.

[0016] As described above, due to the adoption of the above technical solutions, the present application has the following beneficial effects:

[0017] 1. This solution weakens interference at its source by using a pre-filter circuit to suppress common-mode interference with a common-mode inductor, filter differential-mode interference with a ceramic capacitor, and protect against overvoltage with a varistor. The signal processing circuit uses a high-performance chip to further process the signal and reduce interference errors. The signal isolation and amplification circuit further isolates interference and amplifies the signal. This series of designs forms a multi-layered anti-interference system, which, compared with existing technologies, can more effectively ensure stable signal transmission and accurate processing, significantly improving measurement accuracy and stability.

[0018] 2. This solution's composite power supply circuit combines optimized optical power supply, wireless charging, and power management energy storage. Optimized optical power supply improves conversion efficiency, while wireless charging replenishes energy when optical power supply is insufficient, ensuring sufficient power supply under high loads. Supercapacitors reduce the full-load operating time of photovoltaic cells, extending their lifespan. Compared to existing single optical power supply methods, this composite power supply effectively solves the problems of energy supply and equipment lifespan, reduces maintenance costs, and improves the long-term stable operation capability of current transformers.

[0019] 3. The monitoring and control circuit of this solution monitors the parameters of the composite power supply circuit and the operating temperature of the instrument transformer in real time. Based on the data, the microcontroller intelligently switches the power supply mode by controlling relays to ensure stable power supply. Simultaneously, it exchanges data with external devices through the communication circuit to achieve remote monitoring and management. Compared with existing technologies, this not only ensures the stable operation of the instrument transformer under complex conditions but also improves the level of intelligence, allowing maintenance personnel to promptly grasp the equipment status, optimize power system management, and comprehensively enhance the overall performance and value of the instrument transformer. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0021] Figure 1 This is a diagram of the overall working architecture of this utility model;

[0022] Figure 2 This is a schematic diagram of the working architecture of the composite power supply circuit of this utility model. Detailed Implementation

[0023] Clearly, the described embodiments are merely a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0024] In order to make the above-mentioned purposes, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the drawings. In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a variety of ways different from those described herein, and those skilled in the art can make similar improvements without departing from the content of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0025] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or a middle element can exist simultaneously. In contrast, when an element is referred to as being "directly" connected to another element, no intermediate element exists. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0026] As shown in FIGS. Figure 1 and Figure 2 An electronic power taking transformer, comprising:

[0027] The pre-filter circuit comprises a common-mode inductor, a ceramic capacitor and a voltage-dependent resistor; two incoming line ends of the common-mode inductor are connected to a small voltage division signal, an outgoing line end of the common-mode inductor is connected to one end of the ceramic capacitor, the other end of the ceramic capacitor is grounded; the voltage-dependent resistor is connected across the small voltage division signal line and the ground between the two ends thereof;

[0028] In implementation, the pre-filter circuit is used for pre-processing the small voltage division signal output from the transformer to reduce the influence of electromagnetic interference on the subsequent circuit. The common-mode inductor suppresses common-mode interference signals by using the principle of electromagnetic induction. Common-mode interference is usually caused by the influence of the external electromagnetic environment, and produces interference currents of the same direction and amplitude on two signal lines. When the common-mode interference current passes through, the magnetic flux generated in the magnetic core is superimposed on each other, so that the inductance presents a larger impedance, thereby effectively suppressing the transmission of the common-mode interference current.

[0029] Ceramic capacitors filter differential mode interference signals according to the characteristics of the capacitor. Differential mode interference refers to the generation of interference currents of equal size and opposite direction on the two signal lines. Ceramic capacitors have low impedance for high-frequency signals and can provide a low-impedance path for differential mode interference currents, allowing them to flow into the ground, thereby achieving the purpose of filtering differential mode interference. Ceramic capacitors of different capacitance values can filter differential mode interference of different frequency bands, achieving more comprehensive interference suppression.

[0030] When a transient overvoltage occurs on the small voltage division signal line, the resistance of the voltage-dependent resistor will decrease rapidly, introducing the overvoltage into the ground, avoiding damage to subsequent circuit components. Under normal voltage conditions, the resistance of the voltage-dependent resistor is very high, almost not affecting the normal operation of the circuit.

[0031] When the electronic power pickup transformer is working, the small voltage division signal source is continuously transmitted from the transformer output to the pre-filter circuit. The common mode inductor first performs common mode interference suppression on the signal. At any time, as long as there is a common mode interference current trying to pass through the signal line, the common mode inductor will generate a large impedance to hinder its passage. At the same time, the ceramic capacitor continuously bypasses the differential mode interference in the signal, directing differential mode interference currents of different frequency bands to the ground. The voltage-dependent resistor is always on standby, and as soon as the voltage on the small voltage division signal line exceeds its nominal voltage, it will act quickly to release the overvoltage, protecting the entire circuit. In the entire process, the three components work together to continuously filter and protect the small voltage division signal, ensuring that the signal entering the subsequent signal processing circuit is as pure as possible, reducing the impact of interference on measurement accuracy and stability.

[0032] The common mode inductor selected is CDRH1270-101M type common mode inductor. This type of common mode inductor has the following parameters: inductance of 100 μH, which can provide sufficient impedance to suppress common mode interference within the common electromagnetic interference frequency range. The rated current is 1 A, which is sufficient to meet the current demand during the transmission of the small voltage division signal, ensuring that under normal working current, the common mode inductor will not be affected by its performance due to overheating and other problems. In addition, its magnetic core material has good magnetic permeability and stability, and can maintain relatively stable inductance performance under different environmental temperatures and electromagnetic environments.

[0033] The ceramic capacitor adopts two kinds of ceramic capacitors with capacitance values of 0.1 mu F (CC0805-104K500NT) and 0.01 mu F (CC0805-103K500NT). The ceramic capacitor with a capacitance value of 0.1 mu F (CC0805-104K500NT) has a withstand voltage value of 50 V, is suitable for filtering differential mode interference signals in a medium-high frequency band, and can provide appropriate impedance in the frequency band to enable the differential mode interference current to smoothly pass through and flow into the ground. The ceramic capacitor with a capacitance value of 0.01 mu F (CC0805-103K500NT) also has a withstand voltage of 50 V, and is mainly used for filtering differential mode interference in a higher frequency band. The two capacitors with different capacitance values cooperate with each other to cover a wide frequency range and more comprehensively filter differential mode interference.

[0034] The pressure-sensitive resistor is selected to be a MYG14K471 type pressure-sensitive resistor. The nominal voltage of the pressure-sensitive resistor is 470 V, which means that when the voltage on the small voltage division signal line exceeds 470 V, the pressure-sensitive resistor will quickly act to release the overvoltage. The through-flow capacity is 10 kA, which can withstand a large instantaneous overcurrent, ensuring that the circuit can still be effectively protected in the event of adverse conditions such as strong electromagnetic pulses.

[0035] In implementation, the small voltage division signal is filtered by the pre-filtering circuit, effectively suppressing common mode and differential mode interference signals, so that the signal entering the subsequent signal processing circuit is more pure. This greatly reduces the influence of interference signals on the measurement results, improves the measurement accuracy of the electronic power taking transformer. In addition, the effective protection of the pressure-sensitive resistor against instantaneous overvoltage avoids damage to subsequent circuit components caused by overvoltage, improving the stability of the entire electronic power taking transformer system. At the same time, the continuous suppression of electromagnetic interference by the common mode inductor and the ceramic capacitor enables the circuit to work stably in a complex electromagnetic environment, reduces signal fluctuations and misjudgments caused by interference, and ensures the reliable operation of the power system.

[0036] The signal processing circuit includes a signal processing chip, an SRAM, a clock chip, and a reset circuit; an analog input pin of the signal processing chip is connected to an output of the pre-filtering circuit, the signal processing chip is connected to data pins, address pins, and control pins of the SRAM through a data bus, an address bus, and a control bus, respectively; a clock input pin of the signal processing chip is connected to a clock output pin of the clock chip; a reset pin of the signal processing chip is connected to an output end of the reset circuit; and the reset circuit is composed of a 10 kΩ resistor and a 0.1 mu F capacitor.

[0037] In specific implementation, the signal processing circuit is used to accurately process the small voltage division signal output by the pre-filtering circuit to obtain accurate power parameter information.

[0038] In the working process of electronic power taking transformer, the signal processing circuit is continuously running. After pre-filtering, the small voltage signal is continuously input to the analog input pin of the signal processing chip. The signal processing chip immediately converts the input signal into digital form through analog-digital conversion. Then, according to the preset program and algorithm, a series of processing is performed on the digital signal. For example, through the digital filter algorithm, the residual interference signal is removed, the calibration algorithm is used to calibrate the amplitude and phase of the signal, and the compensation algorithm is used to correct the signal deviation caused by the characteristics of the transformer or external factors. During the processing, the signal processing chip frequently interacts with the SRAM for data. The data to be processed is written to the SRAM for temporary storage, and then read from the SRAM during processing. The processed results are also stored in the SRAM for further processing or output. The clock signal stably output by the clock chip ensures that each module in the signal processing chip works according to the accurate time sequence, so that the whole processing process is carried out in an orderly manner. If the system abnormally, such as being affected by strong electromagnetic interference, the reset circuit will generate a reset signal and send it to the reset pin of the signal processing chip, so that the chip is reset and the normal signal processing process is restarted.

[0039] Among them, the signal processing chip selects ADSP-BF533 of ADI company. The chip is based on the high-performance Blackfin architecture and has strong digital signal processing capability. The working frequency is as high as 600MHz, which can quickly process a large amount of data. The core power voltage is 1.2V, and the I / O power voltage is 3.3V, which meets the needs of low power consumption and different interfaces. The chip integrates rich peripherals such as cache and DMA controller, which can accelerate data transmission and processing and improve overall performance.

[0040] SRAM uses IS61LV51216 with a capacity of 512K x 16 bits. The working voltage is 3.3V, which has high read and write speed and can meet the requirements of the signal processing chip for fast data access. Its large capacity can store a large amount of intermediate data in the signal processing process, ensuring the continuity of the processing process.

[0041] The clock chip selects DS1302, and the working voltage range is 2.5-5.5V, which can provide a stable 32.768kHz clock signal. The clock signal has high precision, which can effectively ensure the stability and accuracy of the signal processing chip, and has low power consumption, which is suitable for long-term operation of the electronic power taking transformer.

[0042] The reset circuit is composed of a 10kΩ resistor and a 0.1μF capacitor. When the system is powered on, the voltage across the capacitor cannot change suddenly, and the power supply charges the capacitor through the resistor, generating a short low-level signal at the reset pin to achieve system reset. The time constant τ = RC = 10kΩ x 0.1μF = 1ms, which can ensure that the duration of the reset signal meets the reset requirements of the signal processing chip.

[0043] In a specific implementation, the signal processing circuit can process the small voltage division signal with high precision by virtue of a powerful signal processing chip and an accurate algorithm, effectively eliminate interference, and improve measurement accuracy. In addition, the high-speed data storage and reading of SRAM and the stable clock signal of the clock chip ensure the efficiency and stability of the signal processing process. The system can operate stably for a long time, reduces faults caused by data processing problems, and improves the reliability of the electronic power transformer. Secondly, the reset circuit can reset the signal processing chip in time when the system is disturbed and abnormal, so as to restore the normal work. Combined with the reasonable selection of the installation position and the wiring design, the anti-interference ability of the whole signal processing circuit is enhanced, the reliable operation in the complex electromagnetic environment is ensured, the maintenance cost is reduced, and the service life of the equipment is prolonged.

[0044] The signal isolation and amplification circuit comprises an isolation amplifier, an operational amplifier and a resistance-capacitance network; an input pin of the isolation amplifier receives an output signal of the signal processing circuit, and an isolation output pin of the isolation amplifier is connected to an input pin of the operational amplifier; the operational amplifier sets a gain through the resistance-capacitance network. The resistance-capacitance network is composed of a plurality of resistors and capacitors, and is used for adjusting the gain and frequency response of the amplifier.

[0045] In the operation of electronic power taking transformer, the signal output by the signal processing circuit first enters the input pin of the isolation amplifier. The isolation amplifier immediately performs isolation processing on the signal and transmits it to the isolation output pin without electrical connection through the internal isolation mechanism. During this process, external electromagnetic interference is isolated on the input side and cannot affect the output signal. Then, the isolated signal enters the input pin of the operational amplifier. The operational amplifier amplifies the signal according to the gain set by the resistance-capacitance network. For example, if the gain set by the resistance-capacitance network is 10, the operational amplifier will amplify the amplitude of the input signal by 10 times. During amplification, the resistance-capacitance network adjusts the frequency response of the signal at the same time. If there is high-frequency noise in the signal, by reasonably selecting the capacitance value, the operational amplifier can have a low gain for high-frequency noise, thereby suppressing high-frequency noise. For low-frequency interference, by adjusting the resistance value, the amplification performance of the low-frequency band can be optimized to ensure accurate amplification of low-frequency signals. The amplified and frequency response optimized signal can be output to the subsequent power system monitoring equipment in high quality, providing a reliable signal basis for accurate measurement and analysis of power parameters. The isolation amplifier selected is ISO124 type isolation amplifier. It has excellent isolation performance, with an isolation voltage of up to 2500Vrms, which can effectively isolate electrical interference in a high-voltage environment. The precision is ±0.2%, which can ensure the accuracy of the signal during isolation transmission. It has good linearity and can realize high-precision linear isolation transmission within a wide signal range, meeting the high requirements of electronic power taking transformer for signal isolation. The working power supply voltage range is ±15V, which is suitable for common power supply systems. The operational amplifier uses OPA2277 operational amplifier. This amplifier has low noise characteristics, with an input offset voltage of only 10μV, which can effectively reduce noise interference introduced during signal amplification. The open-loop gain is as high as 130dB, which can provide sufficient amplification multiple to meet the demand for signal amplitude improvement. The bandwidth is 10MHz, which has good amplification performance within a wide frequency range and can adapt to signals with different frequency characteristics. The working power supply voltage range is ±2.2V to ±18V, which is convenient for power supply adaptation with other circuit modules. High-precision metal film resistors are selected, such as 10kΩ and 100kΩ resistors. The 10kΩ resistor can be used to set the basic gain ratio, and the 100kΩ resistor can further adjust the gain multiple according to actual needs. Ceramic capacitors are used, such as 0.1μF and 0.01μF capacitors. The 0.1μF capacitor is used to filter low-frequency noise and adjust the frequency response of the low-frequency band; the 0.01μF capacitor is mainly used to suppress high-frequency noise and optimize the frequency response of the high-frequency band. The combination of these resistors and capacitors can flexibly adjust the gain and frequency response of the operational amplifier to adapt to different signal processing needs.

[0046] The composite power supply circuit comprises a light-powered optimization circuit, a wireless charging circuit and a power management and energy storage circuit; the light-powered optimization circuit comprises a laser driver chip, a photoelectric converter and an MPPT circuit; the monitoring and control circuit comprises a temperature sensor, a microcontroller, a voltage and current monitoring chip and a control relay; the power management and energy storage circuit comprises a capacitor and a power management chip; a laser driving output pin of the laser driver chip is connected to a laser, laser is converted into electric energy by the photoelectric converter and input to the MPPT circuit; an output end of the MPPT circuit is connected to a VIN pin of the power management chip and connected to a control pin of the laser driver chip through a control signal line; a transmitting end and a receiving end of the wireless charging circuit transmit energy through wireless signals, and an output of the wireless charging circuit is connected to another VIN pin of the power management chip; the capacitor is connected to a CAP+ pin of the power management chip; the output end of the power management chip supplies power to the pre-filter circuit, the signal processing circuit, the signal isolation and amplification circuit and the monitoring and control circuit.

[0047] In implementation, the light-powered optimization circuit utilizes the photoelectric conversion principle, the laser driver chip accurately controls the laser to emit laser, and the photoelectric converter efficiently converts laser energy into electric energy. The MPPT circuit monitors the voltage and current of the photoelectric conversion output in real time, adjusts the output of the laser driver chip through the control signal line according to the maximum power point tracking algorithm, so that the photoelectric conversion is always maintained near the maximum power point, and the light-powered efficiency is improved. The wireless charging circuit is based on the principle of electromagnetic induction or magnetic resonance, the transmitting end converts electric energy into wireless signals, and the receiving end captures and converts back to electric energy. This process is not limited by physical connection, and in the case of insufficient light power supply, the mutual inductor is supplemented with electric energy. The power management and energy storage circuit is like a power dispatching center, the power management chip integrates the electric energy input by the light power supply and the wireless charging, and reasonably allocates the electric energy according to the power demand of each circuit module. The capacitor acts as an energy storage element, stores electric energy when the power supply is sufficient, releases electric energy during power consumption peak or power supply fluctuation, smooths voltage and ensures stable power supply.

[0048] In the operation of the electronic power-taking mutual inductor, the light-powered optimization circuit starts first. The laser driver chip drives the laser to emit laser, and the photoelectric converter converts the laser into electric energy input to the MPPT circuit. The MPPT circuit monitors and adjusts in real time, so that the light power supply always remains efficient. When the light power supply can meet the demand of each circuit module, the power management chip allocates it to the pre-filter, signal processing, signal isolation and amplification and monitoring and control circuit. At the same time, the capacitor charges and stores energy.

[0049] If the high load operation or poor light conditions, light power supply is insufficient, wireless charging circuit intervention. The microcontroller in the monitoring and control circuit detects power supply abnormalities, control the wireless charging circuit transmission end to start working, to the receiving end of the transmission of energy. The receiving end of the power output to the power management chip, and light power supply for the system power supply. In this process, the power management chip continues to monitor the input power and the use of the circuit module, dynamic adjustment strategy. Capacitor also according to the power supply, timely release or store energy, to ensure the stability and continuity of power supply, to protect the mutual inductor circuit module normal operation. Among them, the laser driver chip MAX3837, it can provide 0-100mA adjustable drive current, suitable for a variety of power laser, working voltage range of 3.0-3.6V, can accurately drive the laser, to ensure stable laser output. Photoelectric converter BPW34F, under 100mW / cm 2 The typical output current can reach 20mA under the intensity of light, the conversion efficiency is high, can effectively convert laser energy into electrical energy. MPPT circuit using dedicated chip MPP6020, can quickly and accurately track the maximum power point, can make the light power supply efficiency increased by about 15%-20%, the working voltage range is 2.7-5.5V. Wireless charging circuit transmission end BQ500210A, working frequency of 13.56MHz, support up to 5W wireless power transmission, input voltage range of 3.6-5.5V. The receiving end of BQ51013A, conversion efficiency of about 80%, the output voltage can be stabilized at 5V, to provide reliable input for power management chip. Capacitor BCAP0350, capacity of 350F, withstand voltage 2.7V, can store a large amount of energy, to deal with power fluctuations. Power management chip TPS62170, input voltage range of 2-5.5V, can provide 3.3V and 5V and other output voltage, to meet the needs of different circuit modules, the maximum output current is 1A.

[0050] The laser driver chip, photoelectric converter and MPPT circuit of the light power supply optimization circuit should be close to the light transmission path to reduce the transmission loss of light energy and improve the photoelectric conversion efficiency. The wireless charging circuit transmission end can be installed in the relatively open position of the low voltage side of the mutual inductor to avoid signal shielding; the receiving end is installed near the high voltage side circuit that needs power supply to ensure efficient energy reception. The capacitor and power management chip of the power management and energy storage circuit are installed in a position convenient for connecting the input and output of each circuit module, close to each power circuit module to shorten the power supply line and reduce the power loss. At the same time, the whole composite power supply circuit should be kept away from other interference sources to prevent electromagnetic interference from affecting the stability of power supply.

[0051] In the PCB design, according to the packaging form of each chip and element, the corresponding pad is drawn. For the laser driver chip MAX3837, MPP6020, BQ500210A, BQ51013A and TPS62170, surface mount technology (SMT) is adopted, the chip pin is aligned with the pad, and then soldered by reflow soldering process to ensure good electrical connection between the pin and the pad. The photoelectric converter BPW34F also adopts SMT installation, and its light receiving surface is directed to the light source. The super capacitor BCAP0350 is large in size, and is installed by plug-in type, and the pin is inserted into the corresponding pad and then soldered firmly. After the welding of each element is completed, it is carefully checked whether the connection is correct, whether there is a virtual welding or short circuit condition, and it is ensured that the circuit installation is correct.

[0052] In specific implementation, the composite power supply mode combines light power supply and wireless charging, which can guarantee stable power supply under different working conditions. The light power supply optimization circuit improves the photoelectric conversion efficiency, and the wireless charging as a powerful supplement intervenes in time when the light power supply is insufficient, ensuring that the transformer can operate stably under various environmental and load conditions; in addition, the MPPT circuit keeps the light power supply in an efficient state at all times, and the power management chip reasonably allocates electrical energy, reducing energy waste. At the same time, the energy storage effect of the capacitor effectively smooths the voltage, improves the power quality, and further improves the overall energy utilization efficiency. At the same time, stable power supply reduces the damage to each circuit module caused by voltage fluctuation, reduces the probability of equipment failure, prolongs the service life of the electronic power taking transformer, reduces the maintenance cost, and improves the reliability of the power system operation.

[0053] The monitoring and control circuit comprises a microcontroller, a voltage and current monitoring chip, a temperature sensor and a control relay; the microcontroller adopts STM32F407VET6; the input end of the voltage and current monitoring chip is connected to the output end of the composite power supply circuit, and the output ends of the voltage and current monitoring chip and the temperature sensor are connected to the input end of the microcontroller; the output end of the microcontroller is connected with the input end of the control relay, and the control relay is connected to the power supply circuit of the composite power supply circuit.

[0054] In implementation, the monitoring and control circuit works continuously. The voltage and current monitoring chip constantly monitors the voltage and current values output by the composite power supply circuit, and converts these analog signals into digital signals, which are transmitted to the microcontroller in real time. The temperature sensor senses the temperature changes of the transformer in real time, and also transmits the temperature data to the microcontroller in the form of digital signals. The microcontroller periodically reads these data and compares them with the internal preset normal working range values. If the voltage, current or temperature data is within the normal range, the microcontroller continues to monitor. Once abnormal data is detected, such as low voltage, which may mean insufficient light power or wireless charging failure, the microcontroller immediately starts the corresponding processing program. It sends control signals to the control relay through the output port, and the contacts of the control relay act to switch to the backup power supply line or adjust the working state of the wireless charging circuit, so that the composite power supply circuit can stably output the required voltage and current. At the same time, the microcontroller can also record the relevant information of the abnormal event, such as the time of occurrence, the type of abnormality, etc., for subsequent fault analysis and maintenance.

[0055] The microcontroller (STM32F407VET6) is based on Cortex-M4 core, with a main frequency of up to 168MHz, and has powerful data processing capability to quickly process data from the voltage and current monitoring chip and temperature sensor. It has rich peripheral resources, such as multiple general-purpose timers, serial communication interfaces, I2C interfaces, etc., which facilitate communication with other chips. Its working voltage range is 2.4V-3.6V, with 1MB of Flash memory and 192KB of SRAM built-in, which can store program code and data during running. The voltage and current monitoring chip uses INA219, with a measurement voltage range of 0-36V, which can meet the common output voltage monitoring needs of the composite power supply circuit. The measurement current range is ±3.2A, with an accuracy of ±0.2%, which can accurately measure the power supply current. It communicates with the microcontroller through the I2C interface, with a maximum communication rate of 400kHz, ensuring fast and accurate data transmission. The temperature sensor uses DS18B20, with a measurement range of -55℃ to 125℃, which can cover various working temperature environments that the transformer may encounter. The accuracy is ±0.5℃, which can accurately measure the temperature. It uses a single bus communication protocol to connect with the microcontroller, with simple hardware connection, only one data line is needed to realize data transmission. The control relay uses G5V-1-DC5 type relay, with a rated working voltage of 5V, compatible with the output level of the microcontroller. The contact load capacity is 2A / 250VAC or 2A / 30VDC, which can meet the switching needs of the composite power supply circuit power supply line, and reliably control the on-off of the circuit.

[0056] In implementation, the intelligent control of the composite power supply circuit is realized through the circuit, and the power supply mode is automatically adjusted according to the monitoring data. When detecting power supply abnormalities, the power supply line is quickly switched or the working state of wireless charging equipment is adjusted to ensure that the transformer always obtains stable power supply, thereby improving the reliability and stability of the equipment. In addition, the abnormal event information recorded by the microcontroller provides a strong basis for the maintenance and management of the equipment. Maintenance personnel can quickly locate the fault cause according to these data, develop targeted maintenance strategies, reduce maintenance time and cost, and improve the operation and maintenance efficiency of the equipment.

[0057] The communication circuit includes a fiber optic communication module, an RS485 communication chip, and a level conversion chip; the output end of the fiber optic communication module is connected to the receiving device of the remote monitoring center; the A and B pins of the RS485 communication chip are connected to the RS485 bus of other local power equipment; the control pin and the data pin of the RS485 communication chip are connected to the GPIO pin and the serial communication pin of the microcontroller; and the input and output pins of the level conversion chip are connected to the serial communication pin of the microcontroller.

[0058] In implementation, the fiber optic communication module transmits data using optical signals, converts electrical signals into optical signals for transmission in optical fibers based on the total reflection principle of optical fibers, and converts the electrical signals back after reaching the receiving end. This method can achieve long-distance, high-speed, and anti-interference data transmission, and is suitable for data interaction with the remote monitoring center. The RS485 communication chip complies with the RS485 communication protocol and transmits data through differential signals. The A and B lines transmit a pair of differential signals, which can effectively suppress common-mode interference and are suitable for communication between multiple devices in a complex electromagnetic environment. The chip receives control signals from the microcontroller through the control pin to determine the data transmission and reception state, and the data pin is responsible for data transmission and reception with the microcontroller. The level conversion chip is used to solve the problem of mismatched levels between the microcontroller and other communication devices. The microcontroller usually uses TTL level, while RS485 communication and other devices may require different level standards. The level conversion chip converts the level through the internal circuit to ensure accurate data transmission.

[0059] In a specific implementation, when the microcontroller has data to be sent to the remote monitoring center, the data is first transmitted to the electro-optical conversion part of the optical fiber communication module in the form of TTL level. The optical fiber communication module converts it into an optical signal, which is transmitted to the receiving device of the remote monitoring center through the optical fiber. The receiving device converts the optical signal back into an electrical signal for processing. To communicate with other local power equipment, the microcontroller controls the transceiver state of the RS485 communication chip through the GPIO pin according to the communication requirements. When data needs to be sent, the microcontroller transmits the data to the data pin of the RS485 communication chip in the form of TTL level. The chip converts it into a differential signal suitable for RS485 bus transmission and sends it to the RS485 bus of other local power equipment through A and B pins. When receiving data, the process is reversed. The RS485 communication chip converts the received differential signal into TTL level data for the microcontroller to read. The level conversion chip monitors the TTL level data of the microcontroller serial communication pin in real time and converts it into a level suitable for the RS485 communication chip or other equipment according to the communication requirements, ensuring accurate transmission of data between devices with different level standards.

[0060] The optical fiber communication module is selected from HFBR-1521Z (transmitting end) and HFBR-2521Z (receiving end). The HFBR-1521Z transmitting end has a working wavelength of 850nm and a data transmission rate of up to 100Mbps, suitable for high-speed data transmission requirements. The typical value of optical output power is -12dBm, which can ensure reliable transmission within a certain distance. The sensitivity of the HFBR-2521Z receiving end is -20dBm, which can effectively receive optical signals and convert them into electrical signals.

[0061] The RS485 communication chip uses MAX485. The working voltage range is 3.0V-5.5V, which is compatible with common microcontroller levels. The data transmission rate is up to 2.5Mbps, which can meet the fast communication requirements. It has ±15kV ESD protection, which enhances the reliability of the chip in harsh electromagnetic environments. The driver output short-circuit current is limited to within 250mA to prevent chip damage caused by short circuits.

[0062] The level conversion chip is selected as MAX232. The working voltage is 5V, and the bidirectional conversion of TTL level and RS232 level can be realized. The internal integrated capacitor charge pump does not need to be externally connected with a complex circuit. The data transmission rate can reach 120kbps, which meets the basic communication rate requirement between the microcontroller and other devices. In the implementation, the transmitting end of the optical fiber communication module, HFBR-1521Z, is installed near the microcontroller and is convenient for connecting the optical fiber, so that the electrical signal can be quickly transmitted to the transmitting end and the optical fiber connection is convenient. The receiving end HFBR-2521Z is generally installed near the interface of the receiving device of the remote monitoring center, so as to reduce the optical fiber transmission loss. The RS485 communication chip MAX485 is installed near the RS485 bus interface of other local power equipment, so as to shorten the connection distance of A and B pins and the bus and reduce signal interference. At the same time, the microcontroller should be kept at a proper distance, so as to facilitate the connection of the control pin and the data pin. The level conversion chip MAX232 is installed between the microcontroller and the RS485 communication chip, near the serial communication pin of the microcontroller, so as to facilitate the level conversion and data transmission.

[0063] The output end of the pre-filtering circuit is connected with the input end of the signal processing circuit; the output end of the signal processing circuit is connected with the input end of the signal isolation and amplification circuit; the output end of the composite power supply circuit is connected with the input end of the pre-filtering circuit, the signal processing circuit, the signal isolation and amplification circuit and the monitoring and control circuit; the input end of the monitoring and control circuit is connected with the output end of the composite power supply circuit, the output end of the monitoring and control circuit is connected with the control relay for switching the power supply mode of the composite power supply circuit, and the communication circuit is connected with the external equipment for data interaction.

[0064] The electronic power-taking transformer is exemplarily illustrated below by means of specific embodiments:

[0065] In the environment of a certain high-voltage substation, the electronic power-taking transformer starts to work. The small voltage division signal is output from the output end of the transformer, firstly enters the pre-filtering circuit. The common-mode inductor (CDRH1270-101M) suppresses the common-mode interference signal, a plurality of ceramic capacitors (0.1 μF CC0805-104K500NT and 0.01 μF CC0805-103K500NT) filter out the differential-mode interference signal of different frequency bands, and the voltage-sensitive resistor (MYG14K471) prevents the instantaneous overvoltage from damaging the circuit. The signal after the preliminary filtering enters the anti-interference signal processing core circuit. The signal processing chip (ADSP-BF533) processes the signal under the stable clock signal provided by the clock chip (DS1302), such as digital filtering, calibration, compensation, etc. The processed signal is isolated by the isolation amplifier (ISO124), amplified to a suitable amplitude by the operational amplifier (OPA2277), and output to the power system monitoring equipment.

[0066] Under normal conditions, the light supply optimization circuit in the composite power supply circuit works. The laser driver chip (MAX3837) drives the high-efficiency laser, and the photoelectric conversion chip (BPW34F) converts the laser energy into electrical energy. The MPPT circuit (MPP6020) monitors the output voltage and current of the photoelectric conversion chip in real time, adjusts the driving current of the laser, and makes the photoelectric conversion efficiency optimal. The converted electrical energy is input to the power management chip (TPS62170).

[0067] When the light supply power is insufficient, for example, in high-load operation or poor light conditions, the microcontroller (STM32F407VET6) in the monitoring and control circuit controls the wireless charging circuit transmitting end (BQ500210A) to work, and transmits energy to the receiving end (BQ51013A) through wireless transmission. The receiving end outputs electrical energy to TPS62170. The super capacitor (BCAP0350) stores electrical energy when the power supply is stable and releases energy when the power supply fluctuates, assisting in stabilizing the power supply. TPS62170 manages and distributes electrical energy from different sources to power various circuit modules.

[0068] The voltage and current monitoring chip (INA219) in the monitoring and control circuit monitors the output voltage and current of the composite power supply circuit in real time, and the temperature sensor (DS18B20) monitors the operating temperature of the transformer. These data are transmitted to the microcontroller (STM32F407VET6) through the I2C interface and single bus. The microcontroller determines the power supply condition and device operating state according to the monitoring data, and switches the power supply mode of the composite power supply circuit through the control relay. At the same time, the microcontroller interacts with external devices through the optical fiber communication module (HFBR-1521Z, HFBR-2521Z), RS485 communication chip (MAX485), and level conversion chip (MAX232) in the communication circuit, and transmits the operating data of the transformer to the remote monitoring center or other power equipment.

[0069] In this implementation, the inductance of the common-mode inductor (CDRH1270-101M) is 100 μH, and the rated current is 1 A. The voltage resistance of the ceramic capacitors 0.1 μF (CC0805-104K500NT) and 0.01 μF (CC0805-103K500NT) is 50 V. The nominal voltage of the voltage-dependent resistor (MYG14K471) is 470 V, and the current capacity is 10 kA. The signal processing chip (ADSP-BF533) operates at a frequency of 600 MHz, and the power supply voltage is 1.2 V (core) and 3.3 V (I / O). The SRAM (IS61LV51216) has a capacity of 512 Kx16 bits and operates at a voltage of 3.3 V. The clock chip (DS1302) operates at a voltage of 2.5-5.5 V and provides a clock signal of 32.768 kHz. The isolation amplifier (ISO124) has an isolation voltage of 2500 Vrms and an accuracy of ±0.2%. The open-loop gain of the operational amplifier (OPA2277) is 130 dB, the input offset voltage is 10 μV, and the bandwidth is 10 MHz. The laser driver chip (MAX3837) has an output current range of 0-100 mA and drives a laser with a wavelength of 850 nm. The photoelectric conversion chip (BPW34F) outputs a current of about 20 mA when the light intensity is 100 mW / cm 2 The wireless charging circuit transmission end (BQ500210A) operates at a frequency of 13.56 MHz and outputs a power of 5 W. The receiving end (BQ51013A) has a conversion efficiency of about 80%. The super capacitor (BCAP0350) has a capacity of 350 F and a voltage resistance of 2.7 V. The power management chip (TPS62170) has an input voltage range of 2-5.5 V, and the output voltage can be set to 3.3 V or 5 V, with a maximum output current of 1 A. The voltage and current monitoring chip (INA219) measures a voltage range of 0-36 V, a current range of ±3.2 A, and an accuracy of ±0.2%. The temperature sensor (DS18B20) measures a range of -55°C-125°C with an accuracy of ±0.5°C. The microcontroller (STM32F407VET6) operates at a frequency of 168 MHz and has a power supply voltage of 3.3 V.

[0070] In addition, since the pre-filter circuit is close to the output end of the transformer, it is easily affected by strong electromagnetic interference, so a metal shield is used for physical shielding. The common-mode inductor, ceramic capacitor, and voltage-dependent resistor are compactly arranged in the shield, and the signal transmission line is as short as possible to reduce electromagnetic coupling interference.

[0071] To ensure the stability and efficiency of signal processing, the signal processing chip (ADSP-BF533), SRAM (IS61LV51216) and clock chip (DS1302) are concentrated in the center area of the PCB. By reasonably planning the PCB wiring, the power supply line and signal line are separated to reduce mutual interference. The reset circuit is close to the reset pin of ADSP-BF533 to ensure the fast and accurate transmission of the reset signal.

[0072] The isolation amplifier (ISO124) and the operational amplifier (OPA2277) are located near the signal output end to reduce the loss in the signal transmission process. The resistance-capacitance network is arranged around the operational amplifier to facilitate the adjustment of the gain and frequency response of the amplifier.

[0073] The laser driver chip (MAX3837) and the photoelectric conversion chip (BPW34F) in the light-powered optimization circuit are close to the optical transmission path to improve the photoelectric conversion efficiency. The MPPT circuit (MPP6020) is adjacent to them for real-time monitoring and control. The transmitting end (BQ500210A) and the receiving end (BQ51013A) of the wireless charging circuit are arranged in appropriate positions to ensure the effectiveness of wireless energy transmission. The super capacitor (BCAP0350) and the power management chip (TPS62170) in the power management and energy storage circuit are arranged together to facilitate the management and distribution of electrical energy.

[0074] The voltage and current monitoring chip (INA219) is close to the output end of the composite power supply circuit to accurately monitor the voltage and current. The temperature sensor (DS18B20) is installed on the transformer housing, which can sense the working temperature of the transformer in real time. The microcontroller (STM32F407VET6) is located in the center of the PCB, which is convenient for data interaction with other circuits. The control relay is close to the power supply line of the composite power supply circuit, which is convenient for fast switching of the power supply mode. The optical fiber communication module (HFBR-1521Z, HFBR-2521Z), RS485 communication chip (MAX485) and level conversion chip (MAX232) in the communication circuit are arranged at the edge of the PCB, which is convenient for connection with external equipment.

[0075] From the implementation, it can be known that through the multi-layer anti-interference design, in the strong electromagnetic interference environment of the high-voltage transformer substation, the electronic power-taking transformer can effectively suppress the interference signal, and ensure the accurate transmission and processing of the small voltage division signal. Experimental tests show that compared with the traditional transformer, the measurement accuracy is improved by about 20%, effectively solving the problem that the measurement accuracy is affected by electromagnetic interference in the prior art. In addition, the composite power supply circuit combines multiple power supply modes, which can automatically switch the power supply mode according to the actual working condition, and ensure that the transformer can provide stable and sufficient power in various situations. In the case of high load operation or insufficient light power supply, the synergistic effect of wireless charging and super capacitor energy storage ensures the normal operation of the transformer, greatly improves the reliability and stability of power supply, and prolongs the service life of the equipment. Secondly, the monitoring and control circuit realizes real-time monitoring and intelligent control of the running state of the transformer, and the operation and maintenance personnel can remotely obtain the running data of the equipment through the communication circuit, discover potential problems in time and process them. This not only improves the operation and maintenance efficiency and reduces the maintenance cost, but also improves the intelligent management level of the power system, and guarantees the safe and stable operation of the power system.

[0076] Although the specific embodiments of the present application are described above, those skilled in the art should understand that these specific embodiments are only illustrative, and those skilled in the art can make various omissions, substitutions and changes to the details of the above method and system without departing from the principles and essence of the present application. For example, combining the above method steps, performing substantially the same function to achieve substantially the same result according to the substantially same method belongs to the scope of the present application. Therefore, the scope of the present application is only limited by the appended claims.

Claims

1. An electronic power taking transformer, characterized by: The application relates to a signal processing circuit, which comprises a pre-filter circuit, a signal processing circuit, a signal isolation and amplification circuit, a composite power supply circuit, a monitoring and control circuit and a communication circuit. The output end of the pre-filter circuit is connected with the input end of the signal processing circuit; the output end of the signal processing circuit is connected with the input end of the signal isolation and amplification circuit; the output end of the composite power supply circuit is electrically connected with the input ends of the pre-filter circuit, the signal processing circuit, the signal isolation and amplification circuit and the monitoring and control circuit; the input end of the monitoring and control circuit is connected with the output end of the composite power supply circuit, the output end of the monitoring and control circuit switches the composite power supply circuit power supply mode through a control relay, and the monitoring and control circuit is connected with external equipment for data interaction through the communication circuit. The pre-filter circuit comprises a common-mode inductor, a ceramic capacitor and a pressure-sensitive resistor; two wire-in ends of the common-mode inductor are connected with a small voltage division signal, the wire-out end of the common-mode inductor is connected with one end of the ceramic capacitor, and the other end of the ceramic capacitor is grounded; the pressure-sensitive resistor is connected across the small voltage division signal line and the ground.

2. The electronic power drawn transformer according to claim 1, characterized in that: The signal processing circuit comprises a signal processing chip, an SRAM, a clock chip and a reset circuit; the analog input pin of the signal processing chip is connected with the output of the pre-filter circuit, the signal processing chip is connected with the data pin, the address pin and the control pin of the SRAM through a data bus, an address bus and a control bus respectively; the clock input pin of the signal processing chip is connected with the clock output pin of the clock chip; the reset pin of the signal processing chip is connected with the output end of the reset circuit; the reset circuit is composed of a 10kOmega resistor and a 0.1 microfarad capacitor.

3. The electronic power drawn transformer of claim 1, wherein: The signal isolation and amplification circuit comprises an isolation amplifier, an operational amplifier and a resistance-capacitance network; the input pin of the isolation amplifier receives the output signal of the signal processing circuit, the isolation output pin of the isolation amplifier is connected with the input pin of the operational amplifier; the operational amplifier sets the gain through the resistance-capacitance network.

4. The electronic power drawn transformer of claim 1, wherein: The resistance-capacitance network is composed of a plurality of resistors and capacitors, and is used for adjusting the gain and frequency response of the amplifier.

5. The electronic power drawn transformer of claim 4, wherein: ​ 6. The electronic power drawn transformer of claim 1, wherein: The composite power supply circuit comprises a light-powered optimization circuit, a wireless charging circuit and a power management and energy storage circuit; the light-powered optimization circuit comprises a laser driver chip, a photoelectric converter and an MPPT circuit; the monitoring and control circuit comprises a temperature sensor, a microcontroller, a voltage and current monitoring chip and a control relay; the power management and energy storage circuit comprises a capacitor and a power management chip; a laser driving output pin of the laser driver chip is connected to a laser, laser is converted into electric energy by the photoelectric converter and input to the MPPT circuit; an output end of the MPPT circuit is connected to a VIN pin of the power management chip and connected to a control pin of the laser driver chip through a control signal line; a transmitting end and a receiving end of the wireless charging circuit transmit energy through wireless signals, and an output of the wireless charging circuit is connected to another VIN pin of the power management chip; the capacitor is connected to a CAP+ pin of the power management chip; an output end of the power management chip supplies power to the pre-filter circuit, the signal processing circuit, the signal isolation and amplification circuit and the monitoring and control circuit.

7. The electronic power drawn transformer of claim 1, wherein: The monitoring and control circuit comprises a microcontroller, a voltage and current monitoring chip, a temperature sensor and a control relay; the microcontroller adopts STM32F407VET6; an input end of the voltage and current monitoring chip is connected to an output end of the composite power supply circuit, and output ends of the voltage and current monitoring chip and the temperature sensor are connected to an input end of the microcontroller; an output end of the microcontroller is connected to an input end of the control relay, and the control relay is connected to a power supply line of the composite power supply circuit.

8. The electronic power drawn transformer of claim 1, wherein: The communication circuit comprises a fiber communication module, an RS485 communication chip and a level conversion chip; an output end of the fiber communication module is connected to a receiving device of a remote monitoring center; A and B pins of the RS485 communication chip are connected to an RS485 bus of other local power equipment; a control pin and a data pin of the RS485 communication chip are connected to a GPIO pin and a serial communication pin of the microcontroller; an input and output pin of the level conversion chip is connected to a serial communication pin of the microcontroller.

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